GB2541673A

GB2541673A - Drive unit for a trailer

Info

Publication number: GB2541673A
Application number: GB1515090.7A
Authority: GB
Inventors: Mark Harrison Jonathan; Olayemi Ajibade John
Original assignee: Purple Line Ltd
Current assignee: Purple Line Ltd
Priority date: 2015-08-24
Filing date: 2015-08-25
Publication date: 2017-03-01
Anticipated expiration: 2035-08-25
Also published as: GB201515090D0; GB201514997D0; GB2541673B

Abstract

The present invention relates to a drive unit 16 for a trailer with incorporated power isolation component or switch 48. The drive unit 16 for a trailer comprises a motor and a drive mechanism 15 which engages and disengages with the trailer wheels to manoeuvre the trailer, the drive mechanism 15 supported by a support member which is attached to the trailer frame, the drive unit 16 having connection to a source for electrical power switchable by the weatherproof power isolation unit 48 attached externally of the trailer.

Description

Drive Unit for a Trailer

BACKGROUND a. Field of the Invention

The present invention relates to a drive unit for a trailer including a power isolation switch. In particular the invention relates to a drive unit for a caravan including an integrated power isolation switch. b. Related Art

Trailers are unpowered vehicles which are designed to be coupled to and then moved by a powered vehicle, for example a car or van. Such trailers include caravans, box trailers, horse boxes and support trailers for boats. Typically the trailer will be moved to its final destination by the powered vehicle; however, in some circumstances subsequent manoeuvring of the trailer without the aid of the powered vehicle may be required.

For example, caravans are usually towed to a suitable site by a car. Once at a site, the caravan is unhitched from the car and the caravan is moved onto a pitch. The driver can try to manoeuvre the caravan directly on to the pitch but this is frequently not possible due to the confined spaces on the site and between pitches. Caravans are unpowered; however, once unhitched, a person or group of people may manually push and/or pull the caravan to the pitch. Alternatively, it is known that a drive system such as a caravan mover can be used to move the caravan on to the pitch. A caravan mover generally comprises a motor or motors controlled by a user. The caravan mover includes engagement means including a drive roller that is selectively pressed against or spaced apart from the outer tread of a wheel of the caravan. The motor is arranged to rotate the drive roller which, through contact with the outer tread of the wheel, rotates the wheel of the caravan. The caravan mover will typically include at least a pair of drive rollers in engagement with two opposed wheels on an axle. Accordingly, through the selective movement of each drive roller and the respective caravan wheels, the caravan can be arranged to independently move forwards or backwards and can be turned in either direction.

The motor of the caravan mover requires an electrical power supply. This power source is generally provided by a battery provided inside the caravan. This battery may be a leisure battery used to power a number of different systems on the caravan.

It is known to provide a power isolation switch adjacent to the battery which can be used to prevent power being supplied to the caravan mover in an emergency, or to shut off the system when not in use. The power isolation switch is typically located in the battery compartment in the caravan, but may be located elsewhere in the caravan, such as adjacent the door of the caravan. This location makes the isolation switch more easily accessible but requires wires to be routed around and through the caravan, which may lead to damage to the shell of the caravan. Wires must then be routed from the isolation switch and battery to the caravan mover via a suitable electrical control unit.

It is an object of the present invention to overcome at least one problem with prior art caravan movers whether referred to herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a drive unit for a trailer comprising: a drive mechanism comprising drive means, a motor and engagement means, the drive means being arranged to rotate a wheel of a trailer and the engagement means being arranged to move the drive means between an engaged position in which movement of the drive means is transmitted to said wheel and a disengaged position in which the movement is not transmitted; a support member on which the drive mechanism is supported; means for mounting the drive mechanism and/or the support member to the trailer; power means for connecting the drive mechanism to a source of electrical power; and a weatherproof power isolation unit attached externally of the trailer, the power isolation unit comprising a power isolation component electrically connected to the power means, the power isolation component having a first state in which electrical power may be supplied to the drive mechanism and a second state in which electrical power is prevented from being supplied to the drive mechanism.

The power isolation component may comprise a power isolation switch, a circuit breaker, a plug and socket, or a fuse. The power isolation component may be weatherproof. Additionally or alternatively the power isolation unit may comprise a weatherproof housing surrounding the power isolation component.

The power isolation unit is preferably attached to the support member or the drive mechanism. The power isolation unit may be attached to a part of the chassis of the trailer. In embodiments in which the power isolation unit is attached to the support member or the drive mechanism, the power isolation unit is, therefore, integral with the drive unit and does not need to be installed on or in the trailer to which the drive unit is attached. This makes installation of the drive unit on a trailer easier. Additionally, providing the power isolation unit on the drive unit means that the power isolation component is always located in the same position on different drive units. This has the advantage that a user will always know where the power isolation component is located, even if the user is operating a different drive unit, for example on a rented trailer.

Typically a trailer will include at least two wheels spaced apart across the width of the trailer. In preferred embodiments, therefore, the support member is an elongate member having first and second ends and the drive unit comprises a first drive mechanism located at or near the first end of the support member and a second drive mechanism located at or near the second end of the support member, first drive means being arranged to rotate a first wheel of the trailer and second drive means being arranged to rotate a second wheel of the trailer. The or each drive mechanism may comprise a mounting bracket for attaching the drive mechanism to the support member.

In some embodiments the power isolation unit is attached to the mounting bracket. In other embodiments the power isolation unit is attached to the support member. Importantly, the power isolation unit should be attached in a position that is easily accessible to a user of the drive unit. In embodiments in which the support member is an elongate member, the power isolation unit is preferably attached at or near an end of the support member.

The drive unit may further comprise a control unit housed in an enclosure secured to the support member. The enclosure for the control unit is preferably waterproof but includes air vents for providing ventilation to the control unit.

The control unit is electrically connected to the drive mechanism and the power isolation component. Preferably the control unit comprises means for receiving signals from a remote control unit. A user may then use the remote control unit to control the operation of the drive unit.

In preferred embodiments the drive unit comprises a battery enclosure secured to the support member, the battery enclosure arranged to house a battery for providing the source of electrical power. The battery enclosure is preferably waterproof but includes air vents for providing ventilation to the battery.

The drive unit preferably comprises cables or wires for electrically connecting a battery to the power isolation component. The battery may be housed in the battery enclosure, if provided, or the battery may be located on or in the trailer.

In order to prevent power being supplied to the control unit or the drive mechanisms when the drive unit is not in use, or in an emergency, the power isolation component is preferably electrically in series between the battery and the control unit. Furthermore, the control unit will be electrically in series between the power isolation component and the drive mechanism.

In order to provide easy access for a user to the power isolation unit, however, the power isolation component is preferably located spaced apart from both the battery and the control unit. In this way, while the power isolation component is easily accessible, the battery and the control unit may both be located in sheltered or enclosed locations.

In embodiments in which the power isolation unit comprises a housing, the housing preferably comprises a cover plate that is hingedly connected to a side wall of the housing. In preferred embodiments the hinged connection is located along a lower edge of the housing when the drive unit is mounted to a trailer.

The support member may comprise a hollow tubular member. In these embodiments the power isolation unit may be at least partly received in an end of the tubular member. In particular embodiments the housing of the power isolation unit may be at least partly received in an end of the tubular member. The tubular member and the housing may both have a substantially square cross-sectional shape.

The housing may comprise an outer housing member and an inner housing member arranged such that a part of the power isolation component protrudes through an aperture in the inner housing member. The inner housing member may, therefore, be arranged to shield electrical connections to the power isolation component to provide protection from, for example, rain.

In some embodiments the aperture is provided in a base plate of the inner housing member. The power isolation component is in the form of a switch comprising a base assembly including means for providing the electrical connection to the power means and a shaft, the shaft being rotatable to switch the power isolation switch on and off. The inner housing member and switch are arranged such that the shaft protrudes through the aperture and the base assembly is located behind the base plate in the housing.

The inner housing member may comprise a base plate and a side wall extending from a perimeter of the base plate, and in some embodiments the inner housing member is at least partly received within the outer housing member.

Preferably the power isolation component comprises a keyway for receiving a key.

In preferred embodiments the support member comprises a hollow tubular member. Wires providing an electrical connection between the drive mechanism and the power isolation component and at least one of a control unit and a source of electrical power are preferably located within the tubular member.

The drive means preferably comprises a driven roller. In preferred embodiments a surface of the roller for contacting a wheel of the trailer is ridged.

According to a second aspect of the present invention there is provided a wheeled trailer including a drive unit, the drive unit comprising: a drive mechanism comprising drive means, a motor and engagement means, the drive means being arranged to rotate a wheel of the trailer and the engagement means being arranged to move the drive means between an engaged position in which movement of the drive means is transmitted to said wheel and a disengaged position in which the movement is not transmitted; a support member on which the drive mechanism is supported, the drive unit being connected to the trailer by the support member; power means for connecting the drive mechanism to a source of electrical power; and a weatherproof power isolation unit attached externally of the trailer, the power isolation unit comprising a power isolation component electrically connected to the power means.

The power isolation unit may comprise a housing surrounding the power isolation component. The power isolation unit is preferably located proximate a wheel of the trailer. In this position the power isolation unit is easily accessible to a user of the drive unit.

The trailer typically includes two wheels. Accordingly, the support member preferably comprises an elongate member spanning a distance between the two wheels. Additionally, the drive unit comprises a first drive mechanism located at or near a first end of the support member, such that a first drive means is arranged to rotate a first wheel of the trailer, and a second drive mechanism located at or near a second end of the support member, such that a second drive means is arranged to rotate a second wheel of the trailer. Preferably the power isolation unit is located at the first or the second end of the support member.

The trailer may be a caravan.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a drive unit for a trailer according to an embodiment of the present invention, the drive unit being located adjacent two wheels of the trailer;

Figure 2 illustrates a drive mechanism of the drive unit of Figure 1 in a disengaged position relative to a wheel of the trailer;

Figure 3 illustrated the drive mechanism of Figure 2 in an engaged position relative to the wheel of a trailer;

Figure 4 is a perspective view of a drive assembly according to a preferred embodiment of the present invention, the drive assembly including a drive mechanism and an isolation switch assembly;

Figure 5 is rear view of the drive assembly of Figure 4;

Figure 6 is a side view of the drive assembly of Figure 4;

Figure 7 is a top view of the drive assembly of Figure 4;

Figure 8 is a perspective view of the isolation switch assembly of Figure 4 connected to a support member of a drive unit;

Figure 9 is an exploded view of the isolation switch assembly of Figure 8;

Figure 10 illustrates a switch and key of the isolation switch assembly of Figure 8;

Figure 11 is a cross sectional view along the line XI-XI of Figure 12 of an inner housing of the isolation switch assembly of Figure 8;

Figure 12 is a perspective view of the inner housing of the isolation switch assembly of Figure 8;

Figure 13 is a cross sectional view along the line XIII-XIII of Figure 14 of an outer housing of the isolation switch assembly of Figure 8; and

Figure 14 is a perspective view of the outer housing of the isolation switch assembly of Figure 8.

DETAILED DESCRIPTION

Figures 1 to 3 illustrate a drive unit 10 for a trailer according to a preferred embodiment of the present invention. The drive unit 10 comprises an elongate, rigid support member 12 and two drive mechanisms 14, 16.

The drive unit 10 also includes mounting means (not shown) for attaching the drive unit 10 to the trailer. Typically the mounting means will be configured to secure the support member 12 to a part of the chassis of the trailer. The mounting means may be such that the drive unit 10 is permanently secured to the trailer, but in preferred embodiments the drive unit 10 is detachably secured to the trailer. A first drive mechanism 14 is located at or towards a first end 18 of the support member 12 and a second drive mechanism 16 is located at or towards a second end 20 of the support member 12. The spacing between the two drive mechanisms 14, 16, along the length of the support member 12, is such that each of the drive mechanisms 14, 16 is located adjacent a wheel 22 of the trailer. In this regard the length of the support member 12 is preferably adjustable. For example the support member 12 may include at least two sections that are telescopically engaged with each other. The support member 12 typically comprises a hollow tubular member having a substantially square cross-sectional shape.

Each of the drive mechanisms 14, 16 comprises a motor 24, 26, drive means in the form of a driven roller 28, 30 and an engagement mechanism 32, 34. Each drive mechanism 14, 16 is attached to the support member 12 by a suitable mounting bracket 36, 38. Preferably the motor 24, 26, driven roller 28, 30 and engagement mechanism 32, 34 are all attached to the mounting bracket 36, 38 and the mounting bracket 36, 38 further comprises means for securing the bracket 36, 38 to the support member 12. In this way, each drive mechanism 14, 16 may be easily attached to and detached from the support member 12 as a single assembly. Figures 4 to 7 illustrate a preferred embodiment of a drive mechanism 16 and mounting bracket 38.

The driven roller 28 of the first drive mechanism 14 is arranged, in use, to engage with and drive a first wheel 22 of the trailer and the driven roller 30 of the second drive mechanism 16 is arranged, in use, to engage with and drive a second wheel 22 of a trailer. Accordingly, by operating one or both of the drive mechanisms 14, 16, a single wheel of the trailer can be rotated or both wheels can be simultaneously rotated in order to move the trailer in a curved path or in a linear path respectively.

Each driven roller 28, 30 is movable between a disengaged position, shown in Figure 2, and an engaged position, shown in Figure 3. This movement of the driven roller 28, 30 is actuated by the engagement mechanism 32, 34. The engagement mechanism 32, 34 is arranged to move the respective driven roller 28, 30 towards or away from the outer circumferential surface 40 of the wheel 22 (e.g. the tread of the tyre). The engagement mechanism 32, 34 comprises an actuator, for example a piston or an electro-mechanical actuator, to provide the movement of the driven roller 28, 30. In particular, the actuator preferably provides a linear movement between the disengaged potion and the engaged position. The engagement mechanisms 32, 34 may be operated individually or simultaneously to engage one or both of the driven rollers 28, 30.

In the engaged position, an outer peripheral surface 42 of the driven roller 28, 30 is in contact with the tread of the tyre of the wheel 22, and the engagement mechanism 32, 34 causes the driven roller 28, 30 to be urged against the surface 40 of the wheel 22. This permits rotational movement of the driven roller 28, 30 to be transmitted to the wheel 22. Accordingly, in this engaged position, the driven roller 28, 30 can be rotated so as to rotate the wheel 22 of the trailer.

In the disengaged position, the outer surface 42 of the driven roller 28, 30 is spaced apart from the surface 40 of the wheel 22 such that no rotational movement is transmitted.

In the illustrated embodiment each driven roller 28, 30 is a cylindrical roller. The outer surface 42 of the cylindrical roller comprises a contoured or ridged surface 42 in order to provide an improved frictional grip between the driven roller 28, 30 and the surface 40 of the wheel 22.

Each driven roller 28, 30 is connected to the respective motor 24, 26 of the drive mechanism 14, 16 via a suitable gearbox 15. The motor 24, 26 produces the rotational drive for the driven roller 28, 30.

In this embodiment and as shown most clearly in Figure 1, power for the motors 24, 26 is provided by a battery that is located in a suitable battery enclosure 44 secured to and supported on the support member 12. The battery enclosure 44 is waterproof and shock resistant, and is also provided with air vents. The battery enclosure 44 will typically include an opening such that a user can inspect and replace the battery, if necessary.

The drive unit 10 further comprises a control unit that is located in a suitable enclosure 46. The control unit enclosure 46 is also secured to and supported on the support member 12. Again, the enclosure 46 is waterproof and shock resistant.

An electrical circuit is completed by wiring and cables connecting the battery, control unit and drive mechanisms 14, 16. These wires and/or cables are all contained within the support member 12 or within a shroud associated with the support member 12. In particular, the support member 12 effectively provides guide passageways which operate as trunking or conduits for the cables and/or wires.

The drive unit 10, and in particular each of the drive mechanisms 14, 16, is operated by a user using a suitable remote control unit (not shown). Signals from the remote control unit are received and processed by the control unit. The control unit then selectively provides power to one or both of the motors 24, 26 in the drive mechanisms 14, 16 and/or provides a signal or power to one or both of the engagement mechanisms 32, 34.

The remote control unit may, therefore, be used to disengage or engage the driven rollers 28, 30, and apply drive to one or both of the engaged driven rollers 28, 30 to rotate the associated wheel 22 of the trailer, so as to manoeuvre the trailer.

Clearly it is desirable to be able to switch off the drive unit 10 to prevent a person accidentally engaging the driven rollers 28, 30 or applying drive to the rollers 28, 30 when the trailer is in its final position. An on/off switch may be provided on the remote control unit, but this may be easily switched or pressed, for example if a child gets hold of the remote control unit.

It is, therefore, desirable to provide a power isolation unit. In this embodiment a power isolation unit comprising a power isolation component is located on the drive unit 10. The power isolation component is in the form of a power isolation switch, however, it will be appreciated that in other embodiments the power isolation component may be of any other suitable type, such as a button, a circuit breaker or a plug and socket.

The power isolation component should be located so that it is positioned between the battery and the control unit in the electrical circuit. In this way, the battery can be effectively disconnected from the control unit and drive mechanisms 14, 16 so that power cannot be supplied to the motors 24, 26 until the power isolation component is switched on. The power isolation component also provides a safety device which allows power to the drive mechanisms 14, 16 to be interrupted in the event of a fault or other problem.

The power isolation component should, therefore, be located so that it is easily accessible but cannot be accidentally switched on.

In a preferred embodiment, illustrated most clearly in Figures 4 to 9, a power isolation switch 48 is located in a housing 50 at the second end 20 of the support member 12. The housing 50 comprises an outer housing member 52, an inner housing member 54 and a cover plate 56. The housing 50 is weatherproof, such that, when the housing is closed, the housing is sealed to prevent water entering the housing. This prevents or minimises water ingress when it is raining or if water splashes up from a puddle, for example.

The outer housing member 52, shown most clearly in Figures 13 and 14, comprises a hollow tubular member 58. A cross section of the tubular member 58 is substantially square; however, it will be appreciated that in other embodiments the tubular member may have any suitable cross-sectional shape. The tubular member 58 comprises a first portion 60 at a first end 62 of the member 58 for attachment to the support member 12 and a second portion 64 at a second end 66 of the member 58 for receiving the inner housing member 54. The cross-sectional dimensions of the second portion 66 are greater than the cross-sectional dimensions of the first portion 60 and a central, tapered portion 68, therefore, extends between the first and second portions 60, 64.

The dimensions of the first portion 60 are such that the first portion 60 is received within the tubular support member 12 at its second end 20. Suitable securing means may then be used to secure the outer housing 52 to the support member 12. Typically corresponding holes 70, 71 are provided in the first portion 60 of the outer housing member 52 and the support member 12 for receiving screws or bolts.

The isolation switch 48 is located within the second portion 64 of the outer housing member 58. The isolation switch 48 includes a base assembly 72 and a shaft 74 extending from the base assembly 72. The base assembly 72 provides means for mounting the switch 48 in the outer housing member 52 and means for forming an electrical connection to the electrical circuit. Rotation of the shaft 74 about its axis switches the switch on and off.

The inner housing member 54 is shown most clearly in Figures 11 and 12. The inner housing member 54 comprises a substantially square base 76 and side walls 78 extending from the base 76 around the perimeter of the base 76. An aperture 80 is provided in the base 76. Ends of the side walls 78, furthest from the base 76, define an opening 82 of the inner housing member 54. In some embodiments the ends of the side walls 78 may include an outwardly extending rim or flange 84.

The cover plate 56 is pivotally connected to the inner housing member 54 by a hinge 86 such that the cover plate 56 extends over the opening 82 of the inner housing member 54. In this embodiment the cover plate 56 is substantially square and a first part 87 of the hinge 86 is provided at an edge of the cover plate 56 and a second part 88 of the hinge 86 is provided at the end of one of the side walls 78 of the inner housing member 54 and in particular on a part of the flange 84 extending from the side wall 78.

The cover plate 56 may be made from a single sheet of material and may be opaque or transparent. Alternatively, the cover plate 56 may comprise a frame surrounding a window. Making the cover plate 56 from a transparent material or providing a window means that a user can see the position of the switch 48 without needing to open the cover plate 56.

The inner housing member 54 is received in and secured to the second portion 64 of the outer housing member 52. As shown most clearly in Figure 9, the base assembly 72 of the isolation switch 48 locates behind the base 76 of the inner housing member 54 and the shaft 74 of the switch 48 protrudes through the aperture 80 in the base 76.

The provision of an outer housing member 52 and an inner housing member 54 means that the inner housing 54 may be opened to gain access to the shaft 74 of the isolation switch 48 without exposing the base assembly 72 or the electrical circuit. This is of particular benefit if the drive unit 10 is being used in the rain.

It will be appreciated that in other embodiments the housing 50 may not include an inner housing member 54 and the cover plate 56 may be hingedly connected to the second end 66 of the outer housing member 52. In these embodiments a plate member may be provided in the outer housing member to shield the base assembly 72 of the isolation switch 48 and through which the shaft 74 of the switch 48 protrudes.

The inner housing member 54 is preferably secured to the outer housing member 52 and to the support member 12 such that, when the support member 12 is attached to a trailer, the hinge 86 is located along an end of a lower side wall 78 of the inner housing member 54. In this way, the cover plate 56 is moved in a generally downwards direction to open the housing 50 and access the isolation switch 48. This orientation is illustrated in Figures 8 and 9.

In these embodiments the housing 50 includes retaining means (not shown) arranged to retain the cover plate 56 in the closed position in which it extends over the opening 82 of the inner housing member 54. The retaining means may include, for example, a magnetic catch, a hook and eye or a clip.

In embodiments in which the hinge 86 is located along an end of an upper side wall 78 of the inner housing member 54, retaining means are not necessary as the weight of the cover plate 56 will retain it in the closed position. Locating the hinge along the end of an upper side wall 78 can help prevent water ingress into the inner housing member 54, particularly during use of the switch 48.

The shaft 74 of the isolation switch 48 includes a keyway 90 for receiving a key 92. As shown most clearly in Figure 10, a stem or shaft 94 of the key 92 includes a radially extending protrusion 96, and the keyway 90 includes a corresponding groove 98 for receiving the protrusion 96. In this way, the shaft 74 of the switch 48 may only be turned when a suitable key 92, or other tool, is inserted into the key way 90.

The location of the isolation switch 48 within the housing 50, the provision of the cover plate 56 on the housing 50 and the requirement for a key 92 to switch the isolation switch 48 means that that is very unlikely that the isolation switch 48 could be activated or switched on accidentally.

The location of the housing 50 and, therefore, the isolation switch 48 at the end 20 of the support member 12 of the drive unit 10, however, means that the isolation switch 48 is easily accessible to a user. This would not be the case if the isolation switch 48 was located near the battery or control unit as these are located further underneath the trailer and would be difficult to reach.

Although in the illustrated embodiment the housing 50 is secured to the support member 12, it will be appreciated that in other embodiments the housing 50 may be secured to the drive mechanism 14, 16 or the mounting bracket 36, 38 such that the isolation switch 48 is still located proximate an end 20 of the support member 12. In some embodiments the housing 50 may be secured to the drive mechanism 14, 16 or the mounting bracket 36, 38 and the mounting bracket 36, 38 may be detachable from the support member 12. In these embodiments connector plugs may be provided in the base assembly 72 of the isolation switch 48 to enable the switch 48 to be connected to the electrical circuit once the mounting bracket 36, 38 and drive mechanism 14, 16 have been secured to the support member 12.

In the above embodiment a power source in the form of a battery is attached to the support member 12 of the drive unit 10, so that the drive unit 10 is fully self contained. In other embodiments power to the drive unit 10 may be provided by a battery located on or in the trailer. In these embodiments the drive unit 10 comprises electrical connector plugs that allow the battery to be detachably connected to the electrical circuit of the drive unit 10 using suitable power leads. The control unit may also be provided separate from the drive unit, for example within the trailer or within a compartment provided on the trailer. In these embodiments the electrical circuit and/or the battery may be connected to the control unit via electrical connector plugs. The electrical connector plugs may provide a means to quickly disconnect the battery and/or the control unit from the rest of the electrical circuit.

The drive unit 10 will typically include two drive mechanisms 14, 16, one located at or near each end 18, 20 of the support member 12. In some embodiments the drive unit 10 may include four drive mechanisms, each drive mechanism including a motor, an engagement mechanism and a driven roller. In further embodiments, the drive unit 10 may include four driven rollers, a pair of driven rollers being located at or near each end 18, 20 of the support member 12. Each pair of driven rollers may be connected to a single motor and a single engagement mechanism. The provision of four driven rollers allows the drive unit to be engaged with all four wheels of a double axle trailer.

The drive unit 10 of the present invention may be used with any type of trailer that includes wheels. The drive unit is particularly suited to use with larger trailers such as caravans that are difficult to manoeuvre by hand.

Although in the above described embodiment the power isolation unit included a power isolation component surrounded by a housing, it will be appreciated that in other embodiments the power isolation unit may not include a housing. In these embodiments the power isolation component is preferably weatherproof or waterproof. In other embodiments the power isolation component may be surrounded by any suitable casing or cover layer that is waterproof or weatherproof to prevent water ingress to the power isolation component.

The present invention, therefore, provides an improved drive unit for a trailer that includes a power isolation switch that is easily accessible to a user when the drive unit is connected to a trailer.

Claims

1. A drive unit for a trailer comprising: a drive mechanism comprising drive means, a motor and engagement means, the drive means being arranged to rotate a wheel of a trailer and the engagement means being arranged to move the drive means between an engaged position in which movement of the drive means is transmitted to said wheel and a disengaged position in which the movement is not transmitted; a support member on which the drive mechanism is supported; means for mounting the drive mechanism and/or the support member to the trailer; power means for connecting the drive mechanism to a source of electrical power; and a weatherproof power isolation unit attached externally of the trailer, the power isolation unit comprising a power isolation component electrically connected to the power means.

2. A drive unit as claimed in Claim 1, wherein the power isolation component comprises a switch or a plug and socket.

3. A drive unit as claimed in Claim 1 or Claim 2, wherein the power isolation unit is attachable to a part of the chassis of the trailer.

4. A driver unit as claimed in Claim 1 or Clam 2, wherein the power isolation unit is attached to the support member or the drive mechanism.

5. A drive unit as claimed in any preceding claim, wherein the support member is an elongate member having first and second ends and the drive unit comprises a first drive mechanism located at or near the first end of the support member and a second drive mechanism located at or near the second end of the support member, first drive means being arranged to rotate a first wheel of the trailer and second drive means being arranged to rotate a second wheel of the trailer.

6. A drive unit as claimed in any preceding claim, wherein the drive mechanism further comprises a mounting bracket for attaching the drive mechanism to the support member.

7. A drive unit as claimed in Claim 6, wherein the power isolation unit is attached to the mounting bracket.

8. A drive unit as claimed in Claim 5 when dependent on Claim 4, wherein the power isolation unit is attached at or near the first end of the support member.

9. A drive unit as claimed in any preceding claim, further comprising a control unit housed in an enclosure secured to the support member, the control unit being electrically connected to the drive mechanism and the power isolation component and the control unit comprising means for receiving signals from a remote control unit.

10. A drive unit as claimed in any preceding claim, further comprising a battery enclosure secured to the support member, the battery enclosure arranged to house a battery for providing the source of electrical power.

11. A drive unit as claimed in Claim 10, including a battery housed within the battery enclosure, and further comprising cables or wires electrically connecting the battery to the power isolation component.

12. A drive unit as claimed in Claim 11 when dependent on Claim 9, wherein the power isolation component is electrically in series between the battery and the control unit.

13. A drive unit as claimed in Claim 12, wherein the power isolation component is located spaced apart from both the battery and the control unit.

14. A drive unit as claimed in any preceding claim, wherein the power isolation unit comprises a weatherproof housing surrounding the power isolation component.

15. A drive unit as claimed in Claim 14, the housing comprising a cover plate that is hingedly connected to a side wall of the housing.

16. A drive unit as claimed in Claim 15, wherein the hinged connection is located along a lower edge of the housing when the drive unit is mounted to a trailer.

17. A drive unit as claimed in any one of Claims 14 to 16, wherein the support member comprises a hollow tubular member and the housing is at least partly received in an end of the tubular member.

18. A drive unit as claimed in any one of Claims 14 to 17, wherein the housing comprises an outer housing member and an inner housing member and a part of the power isolation component protrudes through an aperture in the inner housing member.

19. A drive unit as claimed in Claim 18, wherein the aperture is provided in a base plate of the inner housing member, the power isolation component comprises a switch, and the switch comprises a base assembly including means for providing the electrical connection to the power means and a shaft, the shaft being rotatable to switch the power isolation switch on and off, and wherein the shaft protrudes through the aperture and the base assembly is located behind the base plate in the housing.

20. A drive unit as claimed in Claim 18 or Claim 19, wherein the inner housing member comprises a base plate and a side wall extending from a perimeter of the base plate, and wherein the inner housing member is at least partly received within the outer housing member.

21. A drive unit as claimed in any preceding claim, wherein the power isolation component comprises a keyway for receiving a key.

22. A drive unit as claimed in any preceding claim, wherein the support member comprises a hollow tubular member and wires providing an electrical connection between the drive mechanism and the power isolation component and at least one of a control unit and a source of electrical power are located within the tubular member.

23. A drive unit as claimed in any preceding claim, wherein the drive means comprises a driven roller.

24. A drive unit as claimed in Claim 22, wherein a surface of the roller for contacting a wheel of the trailer is ridged.

25. A wheeled trailer including a drive unit, the drive unit comprising: a drive mechanism comprising drive means, a motor and engagement means, the drive means being arranged to rotate a wheel of the trailer and the engagement means being arranged to move the drive means between an engaged position in which movement of the drive means is transmitted to said wheel and a disengaged position in which the movement is not transmitted; a support member on which the drive mechanism is supported, the drive unit being connected to the trailer by the support member; power means for connecting the drive mechanism to a source of electrical power; and a weatherproof power isolation unit attached externally of the trailer, the power isolation unit comprising a power isolation component electrically connected to the power means.

26. A wheeled trailer as claimed in Claim 25, wherein the power isolation unit comprises a housing surrounding the power isolation component.

27. A wheeled trailer as claimed in Claim 25 or Claim 26, wherein the power isolation unit is located proximate a wheel of the trailer.

28. A wheeled trailer as claimed in any one of Claims 25 to 27, wherein the power isolation component comprises a switch or a plug and socket.

29. A wheeled trailer as claimed in any one of Claims 25 to 28, wherein the power isolation unit is attached to a part of a chassis of the trailer, the support member or the drive mechanism.

30. A wheeled trailer as claimed in any one of Claims 25 to 28, wherein the trailer includes two wheels, the support member comprises an elongate member spanning a distance between the two wheels, the drive unit comprises a first drive mechanism located at or near a first end of the support member, such that a first drive means is arranged to rotate a first wheel of the trailer, and a second drive mechanism located at or near a second end of the support member, such that a second drive means is arranged to rotate a second wheel of the trailer, and wherein the power isolation unit is located at the first or the second end of the support member.

31. A wheeled trailer as claimed in any of Claims 25 to 30, wherein the trailer is a caravan.

32. A drive unit substantially as herein described with reference to or as shown in the accompanying drawings.